Limit-cycle behavior in one-zone convective models

Abstract

We present the results of a detailed set of one-zone models that account for the coupling between pulsation and convection following the original prescriptions of Stellingwerf (1986). Motivated by the arbitrary nature of the input parameters adopted in this theoretical framework, we computed several sequences of models that cover a substantial fraction of the parameter space and a longer integration time. We also included a turbulent pressure term and found that this physical mechanism plays a crucial role in the pulsation characteristics of the models by removing the sharp discontinuities along the light and the velocity curves showed by models that do not account for turbulent pressure. Finally, we investigated the vibrational and the pulsational stability of completely convective models. We consider as the most important finding of the present work the identification of a well-defined region in the parameter space where they approach limit-cycle stability. Several numerical experiments performed by adopting different values of the adiabatic exponent and of the shell thickness indicate that the coupling between pulsation and convection is the key driving mechanism for LPVs, a finding supported by recent theoretical predictions.

11 pages, 10 figures; accepted for publication in Astrophysical Journal

References in corpus (14)

• Variable Stars in the Magellanic Clouds: Results from OGLE and SIRIUS
• Oscillations of alpha UMa and other red giants
• Classical Cepheid Pulsation Models. III. The Predictable Scenario
• Variable Stars in Leo A: RR Lyraes, Short-period Cepheids, and Implications on Stellar Content
• Red variables in the OGLE-II database. I. Pulsations and period-luminosity relations below the tip of the Red Giant Branch of the LMC
• The Carina Project: II. Stellar Populations
• Theoretical models for Bump Cepheids
• Turbulent Convection and pulsational Stability of Variable Stars I. Oscillations of Long-Period Variables
• Improving the mass determination of Galactic Cepheids
• Solar-like oscillations of semiregular variables
• Large Magellanic Cloud Bump Cepheids: Probing the Stellar Mass-Luminosity Relation
• Hydrodynamical Survey of First Overtone Cepheids
• The angular diameter and distance of the Cepheid Zeta Geminorum
• Classical Cepheid Pulsation Models: IX. New Input Physics

Cited by in corpus (6)

• Asteroseismology and Interferometry
• Interaction Between Convection and Pulsation
• From Solar-like to Mira stars: a unifying description of stellar pulsators in the presence of stochastic noise
• Astrophysics in 2005
• Is the Blazhko effect the beating of a near-resonant double-mode pulsation?
• Self-Excited Pulsations and the Instability Strip of Long-Period Variables: the Transition from Small-Amplitude Red Giants to Semi-Regular Variables